Signaling apparatus for telephone-switchboards.



No. 759,641. PATENTED MAY 10, 1904. E. H. SMYTHB. SIGNALING APPARATUS FOR TELEPHONE SWITCHBOARDS.

APPLICATION FILED JAN. 26, 1903.

N0 MODEL.

Qily:

UNITED STATES Patented May 10, 1904:.

PATENT OFFICE.

EDIVIN H. SMYTHE, OF FREEIORT, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SIGNALING APPARATUS FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION forming part of Letters Patent No. 759,641, dated May 10, 1904.

Application filed January 26, 1903. Serial No. 140,477. (Namodeld To all whom, it may concern:

Be it known that I, EDWIN I-I. SMYTHE, a citizen ot' the United States, residing at Freeport, in the county 01" Stephenson and State of Illi- 5 nois, have invented a certain new and useful Improvement in Signaling Apparatus for Telephone-Switchboards, of which the following is a full, clear, concise, and exact description. Heretoit'ore multiple switchboards have been constructed in two divisionsthat is to say, each line of the exchange has been provided with an answering-jack and line-lamp or annunciator on each of two divisions of multiple switchboard, but with multiple jacks upon I 5 only one of those divisions. In such a divided system the subscriber by examining his directory finds out to which division the subscriber he wishes to talk with belongs, and accordingly signals to the particular division 2 o with which the desired subscriber is connected. My invention is directed toward providing a signaling system particularly adapted for use in such switchboards, wherein a signal, associated with a line at the central oiilce and 2 5 displayed continuously through a momentary actuation by the subscriber of a controllingswitch at a substation of the line, may be withdrawn by means under the control of the subscriber without requiring the cooperation of 0 the central-otfice operator.

In applying my invention to a divided multiple switchboard the circuits and apparatus are so arranged that a subscriber having caused the display of his line-signal at one division by operating one of his signal'keys may by operating another of his signal-keys eflace the signal first displayed and bring about the display of his signal at another division. Replacing the telephone on the book 4 acts to efiace whichever signal is at the time displayed. These results are attained by including a relay in each side of the line which when actuated in response to the control of its associated key at the substation operates to close a locking-circuit for itself controlled by the telephone-switch at the substation, to light a lamp at one of the switchboards, and to shortcircuit, shunt, or in some other way render inert the relay included in the other side of the line. 5

In the accompanying drawing, which is illustrative of my invention, I have shown two telephone-stations with their lines extending to the central oflice and provided with apparatus and circuit connections embodying my invention.

The telephone-station A is provided with the usual receiver, transmitter, induction-coil, condenser, ringer, and automatic gravityswitch, and the signal-keys a I), one in each of the limbs 1 2 of the telephone-circuit. On depressing either key the limb to which it belongs is closed to ground, opening the line at the substation. On being released (the telephone being oif the hook) the key completes 5 the circuit before opening the ground connection. The relays c and d are provided in the circuits of limbs 1 and 2, respectively. The extensions 0 from relay 0 to relay (Z and the extensions y" from relay (Z to relay 0 are ar- 7 ranged as shown. It will be observed thatwhen either of the relays c or cl is operated the corresponding circuit f or a, as the case may be, will be closed and grounded by the armature of the relay that is operated.

At g is shown a battery, which may be of twenty-four volts. The cut-off relay it when excited attracts its armatures and cuts off the individual signaling apparatus.

Signal-lamp I: and answering-jack Z are at 30 one of the two divisions of the multiple switchboard, while the other signal-lamp, Z5, and answering-jack Z of the line of station A are located in the other division of the multiple switchboard. The relays e (Z it may be of, 5 say, live hundred ohms resistance each.

m m, &c., represent multiple jacks ol the divisions to which signal I: and answeringjaclz Z belong. The lincoi' station A, according to the divided-multiple-switchboard plan, 9 would not be provided with multiple jacks at the division where signal It and answeringjack Z are placed. Station A is provided with apparatus similar to that at station A, and similar apparatus and circuit connections are provided at the central station for the provided.

telephone-line of station A such apparatus being marked by letters of reference to correspond with the lettering of the apparatus at station A.

A cord-circuit is shown for connecting the lines together at one of the divisions. This cord-circuit consists of a pair of plugs 12. 7L, their tips being connected by strand 3 and their sleeves by strand 4. provided in the tip-strand, as shown. The usual ringing-key p and listening-key q are The battery 9* is connected with the repeating coils and circuits, as indicated. The repeating-coil s is provided with an armature and contact, as shown. The clearingout signals are shown at Z Z.

I will now describe the operation of my invention. The subscriber at station A, we will assume, has by his directory ascertained that the subscriber wanted at station A belongs to the same division as does his own line, which we will call the first division, or Division A. Subscriber A will remove his telephone from its hook and depress his key a, which will operate the line-signal in at said Division Athat is to say, on depressing key (Z limb l is closed to ground at the subscribers station, and current from battery g is thus directed through lamp 7c, (without lighting the same,) through the winding of relay 0, over said limb 1 to the ground thus formed at station A. The armature of relay cwill be attracted and will close the contacts of the circuit f to ground. The key CZ having been released and the telephone being removed from the switch, the circuit of limb 1 will be transferred from ground at station A, through said station A by the telephone-switch to limb 2, thence to the central oflice, and thence to one of the Wires of the circuit f, to the armature of relay c, and thence to ground that'is to say, the first impulse of the battery 9 will be to ground formed by key a at station A, and immediately on releasing said key (Zthe circuit of battery Q will be transferred to the ground formed at relay 0. Keysaand 5 are so constructed that one circuit to ground is completed before the other is broken in order to prevent any intermission of the flow of current. through the line-relay which has been actuated. It should be remarked that the resistance of the circuit including individual line-signal Zn is so great as to prevent the operation of said signal. The line-signal Z; at Division A, however, is included in a local circuit, formed by the closing of the armature of relay 0, said circuit extending from the free pole of battery g through an extension f, controlled by relay 0, and the armature of said relay to earth. Hence line-signal Z; will be disclosed immediately on depressing key a and will remain disclosed as long the telephone at station A is removed from the switch or until the callis answered by inserting plug a in answering-jack Z or until key 7) is pressed The relays 0 0 are.

to display signal k hen relay 0 draws up its armature in completing circuit f, it shortcircuits relay (Z, so that relay (Z is not excited by current flowing in limb 2 of the line. lVhen plug a is inserted in response to the disclosure of signal Zn, current from battery 1' is directed over wire 4 through relay it, thus cutting off the signaling apparatus of the line, and the armature of repeating-coil s is closed, connecting battery with the circuit of supervisory signalst t; Lamp 25, however, will not light, since its circuit will be open at the contact of relay 0,. the battery-circuit being closed through said relay 0 over limb 2 through substation A and back over limb 1. Supervisory signal-lamp 25 will, however, be included in a circuit extending from the free pole of battery 0' through the armature and front contact of repeating-coil sand the armature and back contact of relay 0. to earth. Said lamp Z will thereupon become illuminated. The operator ascertaining that subscriber A is called for proceeds to test the line, make the connection, and signal subscriber A in the usual manner. Vi hen subscriber A responds to the call, relay 0 becomes energized and breaks the circuit above traced, including signal-lamp Z, whereupon said lamp is extinguished. As soon as the conversation is finished and both subscribers hang up their telephones the supervisory signals 25 Z will be disclosed, and the plugs will be pulled out.

I have thus described the manner of connecting and disconnecting lines of stations A and A upon Division A of the multiple switchboard. Assume now that subscriber A wishes connection with some subscriber of the other division, the one at which his line-signal 7c and answering-jack Z are placed, which we will call the second division, or Division B. I have not deemed it necessary to show the circuit connections of such subscriber, since my invention relates more particularly to the control by a subscriber of the signals is and 7c and his ability to select the right one as occasion requires. Subscriber A, having ascertained that the subscriber wanted is of Division B, will take down his telephone and depress key 6. Circuit from battery 9 will now be completed through signal Z: and limb 2 to ground at the signal-key Z. The resistance of the circuit is so great that signal Z; will not be operated; but the relay (Z will be operated and the circuit a closed. The closure of circuit 6 completes the circuit of signallamp It" directly to earth and illuminates it and closes a short circuit of relay 0 in the other limb of the line, thus rendering it inertto current returning over limb 1 of the line when key 6 is released. Releasing keybcompletes the locking-circuit of relay (Z through both limbs of the line and the switches at substation A to earth at the central oliice by way of conductor a, controlled in contacts of relay I3 (Z. The continued display of signal 71: after the momentary depression of key I) is thus effected. If after the signal It has been displayed the subscriber should desire for any reason to withdraw signal 7; and display signal 1:: in its stead,' he has merely to press key a. The depression of key a opens thelocking-circuit of relay (Z, permitting the relay to release its armature, upon which relay 0 is actuated to'light lamp Z': and short-circuit relay (Z, as already described, or if the subscriber after having caused the display of one of the signals desires to withdraw the call he may do so by replacing his telephone on its hook, which breaks the locking-circuit operating to effect the continued display of the signal.

. In the drawing 1 have shown two batteries g and 1'. 1t will be .understood that in practice these batteries would ordinarily be the i believe, the first realization of a system whereby asubscriber who has erroneously displayed a signal at one division may immediately with draw said signal and display a signal at the division intended.

It will be understood that in place of the earth as a return-conductor from the lower contacts of the keys a Z) to the battery g a metallic conductor may be employed. The circuit of the battery when completed over the two limbs of the telephone-line to include the windings of a relay and the contacts thereof may be called the locking-circuit.

Certain portions of my apparatus may be used advantageously in telephone systems other than divided systems. 1 therefore do not limit myself to combinations embracing two relays and two signabkeys except as expressed in certain of the claims, which follow.

1 claim- I 1. The combination with a telephone-line, of a source of current and a signal-controlling magnet connected with one limb of the line at the central oflice, a key at the substation controlling a connection from said limb to a return-conductor, a switch at the substation controlling a bridge of the two limbs, and a connection of the other limb to said returnconductor at the central ofiiee, controlled by said magnet, whereby the continued excitement of the magnet after the actuation of said key is dependent upon the switch at the substation.

2. The combinationwith a metallic-circuit telephone-line extending from a substation to a central oflice, of a source of current at the central oifiee having one pole connected to a return-conductor and the other pole connected with one limb of said metallic circuit, a signalcontrolling magnet at the central office having a winding included in the circuit of one side of the line, a key at the substation adapted to connect the line with said return-conductor,

a switch at the substation controlling a bridge divisions, one in each line conductor, relays controllmg said signals, a central source of current, special keys at the substation adapted to complete the circuit of said relays respectively', a telephone-switch at the substation, and a locking-cireuit for each relay completed in contacts thereof, said locking-circuit including both line conductors and being controlled by said substation telephone-switch, substantially as and for the purpose set forth.

4. The combination with the telephone-line, of the switch at the substation for connecting and disconnecting the limbs thereof, signalkeys a and I), one in each limb, battery connected through signal-1amps at different divisions of the switchboard, and relays of high resistance, one in each limb .and arranged to control the circuits through said lamps; whereby the subscriber may light and elface the different lamps at will, substantially as described.

5. The combination with a telephone-circuit, of. a continuity signal-key in each limb thereof at the subscribers station, correspond ing relays; lamp-signals at the central ofiice, one for each relay and controlled thereby, the telephone-switch, a battery, and the circuit connections, whereby the lamp-signals may be alternatively disclosed and elfaced, substantially as described.

6. The combination with a telephoneline extending in two limbs from a substation to the poles of a central source of current, a relay 0 at the central office, a circuit f controlled thereby, a signal-lamp K in said circuit, a key a at the substation, a circuit for said relay 0 controlled thereby, a telephone-switch at the substation, and a locking-circuit for said relay controlled by said telephone-switch.

7. The combination with a metallic-circuit telephone-line extending from a substation to a central oflice, of signal-controlling electromagnets at the central oflice included one in each limb of the metallic circuit, a central source of current, a bridge of the metallic circuit at the substation, keys at the substation, one for each of the said magnets, each key being adapted when operated to open said bridge and to connect the limb of the line with a return-conductor to actuate the corresponding magnet, and a locking-circuit for each of said magnets including both limbs of the metallic circuit and the said bridge at the substation substantially as described.

IIO

8. The combination with a metallic-circuit telephone-line extending from a substation to a central oflice, of two signals, electromagnets, one in each limb of the line, a source of current, keys at the substation, one associated with each limb of the line, for controlling the corresponding electromagnets, a bridge of the line at the substation, a locking-circuit for each electromagnet including the bridge and both limbs of the line, and completed in switchcontacts of the same electromagnet, and means controlled by each electromagnet for efi ecting the display of one signal and preventing the display of the other signal.

9. The combination with a metallic-circuit telephone-line extending from a substation to a central ofiice, of a source of current at the central oflice having one pole connected to a return-conductor and the other pole connected to both limbs of said line, relays of high resistance and signal devices, one of each being connected serially between the source of current and each limb of the line, a bridge of the line at the substation, a telephone-switch controlling said bridge, keys at the substation, one associated with each limb of the line and adapted when operated to interrupt said bridge and connect the limb of the line with which it is associated to said return-conductor, two normally open branches to said return-conductor from each limb of the line at the central office, one branch extending from each side of the relay included in that side of the line, and contacts of each relay controlling the continuity of the branches which extend from the other limb of the line, substantially as described.

10. The combination with a metallic-circuit telephone-line extending from a substation to a central oifice, of relays, one connected in each limb of the line at the central office, a source of current having one pole connected with a return-conductor and the other pole connected to both limbs of the line through said relays, keys at the substation adapted each to connect the limb of the line with which it is associated to said return-conductor to direct current through and actuate the corresponding relay, a bridge of the circuit at the substation controlling the same, and a normally open branch from each limb of the line at the central ofiice to the return-conductor,

adapted to be completed in switch-contacts of the relay associated with the other limb of'the line, and circuit connections controlled by each relay for rendering the other relay inert.

11. The combination with a metallic-circuit telephone-line extending from a substation to a central office, of relays and signals, one of each being connected with each limb of the line at the central oflice, a source of current having one pole connected with a return-conductor and the other pole connected to both limbs of the line through said relays and signals, a bridge of the line at the substation, keys at the substation each adapted to break said bridge and to connect the limb of the line with which it is associated to said returnconductor to direct current through and actuate the corresponding relay, said current being insufficient to operate the associated signal, and a circuit to said return-conductor from each limb of the line controlled in contacts of the relay associated with the other limb, adapted when completed to render inert the relay connected with the limb of the line with which said branch is associated, to actuate the corresponding signal, and to complete a locking-circuit for the relay connected with the other side of the line, said locking-circuit including both limbs of the line, substantially as described.

12. The combination with a metallic-circuit telephone-line extending from a substation to a divided multiple switchboard; of two linesignals associated with the conductors respectively of said metallic circuit, and placed at the respective switchboard-divisions; a local or switchboard circuit for each line-signal; a relay for each of the said metallic-circuit conductors, controlling the associated line-signal local circuit thereof; and a normally open shunt about each relay leading through switchcontacts of the other; whereby on the operation of either relay the corresponding linesignal is also operated, and the other relay held inert; substantially as set forth.

In witness whereof I hereunto subscribe my name this 22d day of November, A. D. 1902.

EDWIN H. SMYTHE.

l/Vitnesses:

GEORGE P. BARTON, JOHN G. ROBERTS. 

